This invention relates generally to ladders that incorporate safety features, and more particularly to ladders that provide warnings to a user that the ladder is about to tip.
Conventional household ladders (including step ladders and extension ladders) have enjoyed near universal acceptance by combining their ability to facilitate reaching remote areas with portable, human-carryable packaging. Nevertheless, conventional household ladders tip over when the combined center of gravity of a user (i.e., climber) and the ladder moves to a point beyond the foot of the ladder. In such a case a moment is produced, and while the frictional force of the wall tends to counter the torque caused by the moment, often it is not enough to prevent the ladder from tipping. Unbalance leading to ladder tipping typically occurs in one of two ways. In the first, the climber leans over too far to one side such that the center of gravity is beyond the ladder footprint. In the second, the ladder is placed leaning to one side, such as due to being placed on an uneven surface. In this latter case, the vertical line from the center of gravity of the ladder may not initially be beyond a foot of the ladder; however, as the climber moves higher up the ladder, the combined center of gravity of the ladder and the climber moves outside the ladder feet. Even though the imbalance leading to tipping of a ladder develops only gradually in this second instance, the climber remains unaware of the hazard until it is too late and the ladder tips over.
Accordingly, there exists a need for improvements in ladder design to enhance ladder safety, especially as it relates to ladder tipping. Moreover, there exists a need for notorious warnings that can alert a ladder user that a dangerous operating condition is imminent. Furthermore, there exists a need for a ladder that can deploy additional stabilizing members in response to dangerous ladder operating conditions. In addition, there exists a need for such a ladder that provides the above while being inexpensive and without sacrificing its human-carryable attributes.